FIELD OF THE INVENTION
The invention relates to a power MOSFET with a semiconductor body having an inner zone of a first conduction type and a given dopant concentration, at least one base zone of a second conduction type being adjacent the inner zone and a first surface of the semiconductor body, at least one source zone being embedded in each base zone, and at least one drain zone adjacent one of the surfaces of the semiconductor body.
Such power MOSFETs have long been known. The unipolar conduction mechanism of those MOSFETs means that the conducting-state DC resistance depends essentially on the doping of the inner zone. In power MOSFETs of over 500 V blocking voltage, the conducting-state DC resistance becomes higher than in comparable bipolar transistors. Increasing the doping is not an option, because that would reduce the blocking capability.